Windshield wiper system

ABSTRACT

In a preferred form, this disclosure relates to a windshield wiper system wherein the direction of the rotation of an electric motor is periodically reversed to effect oscillation of a wiper through a wipe cycle having a first angular stroke when a manual switch is placed in a first on position and is reversed periodically faster to effect oscillation of the wiper through a wipe cycle having a second angular stroke which is less than the first angular stroke when the manual switch is placed in a second on position. The windshield wiper system includes relay operated switch means which is operatively connected with the motor and the manual switch for reversing the direction of rotation of the motor and a plurality of position switches which are interconnected with the relay operated switch means and actuated by a cam on the drive shaft of the motor for controlling energization and de-energization of the relay operated switch means to effect the periodic reversal of the motor.

United States Patent Elliott Sept. 5, 1972 [54] WINDSHIELD WIPER SYSTEM[72] Inventor: James 0. Elliott, Xenia, Ohio [73] Assignee: GeneralMotors Corporation, Detroit, Mich.

[22] Filed: Aug. 9, 1971 [2]] Appl. No.: 170,112

52 us. 01 ..318/443, 318/444, 3 1 8/DIG. 2 51 1111. C1. ..H02p 1/04 58Field of Search ..3l8/443, 444, ms. 2;

[56] References Cited UNITED STATES PATENTS 2,748,612 6/1956 Dyer et a1...15/230.13 x 3,253,206 5/1966 Romanowski ..3 1 8/DIG. 2 3,609,4969/1971 Peroy ..3l8/444 Primary ExaminerBenjamin Dobeck Attorney-W. E.Finken et a1.

[57] I ABSTRACT in a preferred form, this disclosure relates to awindshield wiper system wherein the direction of the rotation of anelectric motor is periodically reversed to effect oscillation of a wiperthrough a wipe cycle having a first angular stroke when a manual switchis placed in a first on position and is reversed periodically faster toeffect oscillation of the wiper through a wipe cycle having a secondangular stroke which is less than the first angular stroke when themanual switch is placed in a second on position. The

.windshield wiper system includes relay operated switch means which isoperatively connected with the motor and the manual switch for reversingthe direction of rotation of the motor and a plurality of positionswitches which are interconnected with the relay operated switch meansand actuated by a cam on the drive shaft of the motor for controllingenergiza- 5 tion and de-energization of the relay operated switch meansto effect the periodic reversal of the motor.

5 Claims, 2 Drawing Figures WINDSHIELD WIPER SYSTEM 1 The presentinvention relates to a windshield wiper system, and more particularly toa windshield wiper system which is selectively operable to oscillate awindshield wiper across a windshield of an automotive vehicle throughwipe cycles having two different angular strokes.

l-leretofore, electric windshield wiper systems have been provided whichinclude control mechanisms to vary the angular wipe stroke or sweep ofthe windshield wiper between a wide and a narrow angular stroke. Forexample, see US. Pat. Nos. 2,173,447 and 2,800,675. These windshieldwiper systems generally provide for a variation of the angular wipestroke or sweep through various mechanical means, such asby lengtheningor shortening the length of the throw of the systems drive linkage asdesired by the operator.

Further, my co-pending US. Pat. application Ser. No. 78,439 discloses anelectric windshield wiper system with a drive linkage which oscillatesits windshield wipers through a wipe 'cycle having a first angular wipestroke when a DCmotor is driven in one direction and which oscillatesits windshield wipers through a wipe cycle having a second angular wipestroke less thanthe first angular stroke when the DC motor isperiodically reversed. That electric windshield wiper system included atwo-speed DC motor which is normally driven in one direction at either ahigh or low with the motor means and having first and second onpositions for controlling energization of the motor means, a relayoperated switch means operatively connected with the motor means and themanual switch means for reversing the direction of rotation of the motormeans, a cam means rotatable with the drive shaft means, and a pluralityof position switches interconnected with the relay operated switch meansand the manual switch means for controlling energization andde-energization of the relay operated switch means to effect periodicreversal of the motor means, and in which the position switches areactuated by the rotatable cam means to effect continuous oscillation ofthe wiper through a wipe cycle having a first angular stroke when themanual switch is in its first on position and effect continuousoscillation of the wiper through a wipe cycle having a second angularstroke which is less than the first angular stroke when the manualswitch is in it second on position. I

Another object of the present invention is to provide a new and improvedwindshield wiper system as set forth in the preceding object and whereinthe reversible electric motor means has only one speed.

These and other objects of the present invention are accomplished, in apreferred embodiment, by providing a windshield wiper system which isoperatively connected with a DC power source and whichhas a reversible,single speed electric motor means for rotating a speed as controlled bya manual control switch and which rotates a drive shaft to drive thedrive linkage. The drive linkage drives the windshield wipers through afirst angular stroke in one direction for the first 180 of rotation ofthe drive shaft and then drives the wipers through a reverse stroke inthe opposite direction for the next 180 of rotation of the drive shaft.The drive linkage thereby oscillated the system's windshield wipersthrough a wipe cycle having a first angular wipe stroke for each 360 ofrotation of the drive shaft. The windshield wiper system of myco-pending application also includes a double pole, double throw relaywhich can be energized when the DC motor is being driven at either itshigh or low speed to reverse the direction of the current through the DCmotor and thereby reverse the direction of rotation of the DC motor. Therelay is energized in response to the closing of a segment wipe switchand thereafter is periodically de-energized and energized in response tothe opening and closing of a pair of switches by a cam on the driveshaft of the DC motor. The switches are positioned relative to the driveshaft such that the direction of rotation of the motor and hence thedrive shaft is caused to be reversed after a rotation of the drive shaftof less than 180. It should be understood from this that it is thereversal of the motor and not the drive linkage which reverses thedirection of the movement of the wipers when the segment wipe switch isclosed. The windshield wipers are drive shaft means for driving awindshield wiper. The energization of the motor means is controlled bymanual switch means which has first and second on positions. Thewindshield wiper system also includes a double pole, double throw relaywhich is connected with the motor means and which has a relay coilconnected with the manual switch means for reversing the electrical paththrough the motor means when energized in order to reverse the directionof rotation of the motor means. The windshield wiper system furtherincludes first and second position switch means which are connectedbetween the relay coil and the manual switch means and which areactuated by a cam means driven by the drive shaft.

The first position switch means comprises first and second switcheswhich are responsive to first predetermined angular movements of the cammeans less than 360 when the manual switch means is in its first onposition for alternately energizing and de-energizing the relay coil toperiodically reverse the direction of rotation of the motor means andoscillate the wiper means at a first wipe frequency through a wipe cyclehaving a first angular stroke. The second position switch meanscomprises third and fourth switches which are responsive to secondpredetermined angular movements of the cam means less than the firstangular movements when the manual switch is in its second on positionfor alternately energizing and de-energizing the relay coil to reversethe direction of rotation of the motor means periodically faster wherebythe motor means oscillates the wiper means at a second wipe frequencygreater than the first wipe frequency and through a wipe cycle having asecond angular stroke less than the first angular stroke when the manualswitch means is in its second on position.

These and other objects of the present invention will become more fullyapparent from the following description and drawing wherein:

FIG. 1 is a fragmentary front elevational view of an automotive vehicleembodying the windshield wiper system of the present invention and whichgraphically shows the first and second angular wipe strokes throughwhich the windshield wiper can be oscillated; and

FIG. 2 is a schematic control diagram of the windshield wiper system ofthe present invention.

As representing a preferred embodiment of the present invention, thedrawing shows an electric windshield wiper system having a suitabledrive linkage means 12 which is adapted to oscillate a conventionalwindshield wiper arm and blade assembly 14 through a wipe cycle acrossthe outer surface of the windshield 16 of an automotive vehicle 18. Thewiper arm and blade assembly is rotatably supported in a conventionalmanner at its lower end by the body structure 19 of the vehicle 18. Whenthe windshield wiper system 10 of the present invention has beenactuated, the linkage means 12 oscillates the windshield wiper arm andblade assembly 14 in a conventional manner through a wipe cycle havingeither a first wipe stroke, herein shown as having an angle equal to theangle A, or a second wipe stroke, herein shown as having an angle equalto the angle B, which is less than the first angular stroke. It shouldbe understood that a wipe cycle is meant to include the movement ofwindshield wiper arm and blade assembly 14 through both an outboardstroke and an inboard stroke. That is, movement from its inboard end ofthe stroke, A; or B to the outboard end, A or B and back to the inboardend. Further, the windshield wiper system 10, when deactivated, isoperative to move the windshield wiper arm and blade assembly 14 anadditional angular movement, herein shown as having an angle equal tothe angle C, from the inner end A of the first angular stroke A to adepressed park position P immediately adjacent the bottom of thewindshield 16.

It should also be understood that the windshield wiper system 10includes a pair of windshield wiper arm and blade assemblies 14 whichare located in conventional positions on both the passenger and driversides of the vehicle 18, although only one is shown.

The windshield wiper system 10 broadly comprises a DC motor means 20which drives a drive shaft 22 and a manual control switch 24 whichcontrols energization of the DC motor 20. The system 10 also includes arelay operated switch means 26 which reverses the direction of thecurrent through the DC motor to reverse the direction of rotation of theDC motor and position switch means 28 for alternately energizing andde-energizing the relay operated switch means 26 in response topredetermined angular movements of the drive shaft 22 to reverse thedirection of rotation of the DC motor 20. Referring to Fig. 2, the motormeans 20 is herein shown as a reversible single speed, permanent magnetDC motor having a wound armature 34 for driving the drive shaft 22 via aconventional gear reduction unit (not Shown). It should be noted thatthe motor means 20 could also be any suitable wound field motor. Fixedto the drive shaft 22 is a first cam 22a. The drive shaft 22 is suitablyconnected with the drive linkage means 12, shown in FIG. 1, to oscillatethe windshield wiper arm and blade assembly 14.

The manual control switch means 24 could be of any suitable orconventional construction and is schematically shown as including amanually manipulatable control bar 37. The control bar 37 is movablebetween an 011 position, as shown by the solid lines in FIG. 2, a firston position, as shown by the dash lines in FIG. 2, and a second onposition, as shown shown by the phantom lines in FIG. 2. The control bar37 has a first contact portion 39 which is grounded via conductor 38 toground G and a second contact portion 40. The manual control switchmeans 24 also includes four stationary contact members 42-45. When thecontrol bar 37 is moved from its ofi position to its first on position,the first contact portion 39 connects the stationary contact members 42and 43 with ground G and the second contact portion 40 engages thestationarycontact member 44. When the control bar 37 is moved from itsfirst on position to its second on position, the first contact portionconnects the stationary contact members 42 and 45 with ground G and thesecond contact portion 40 is disengaged from the stationary contactmember 44.

The relay operated switch means 26 controls the.

electrical path or the direction of the current to the armatures winding(not shown). The relay operated switch means 26 comprises four fixedcontacts 47-50, two movable contacts 51 and 52, and a relay coil 54.Fixed contact 48 is connected with the fixed contact 50 via conductor 56and with one side of the armatures winding via conductor 58. The fixedcontact 47 is connected with the fixed contact 49 via conductor 60 andwith the other side of the armatures winding via conductor 62. Themovable contact 51 is connected with the positive terminal of thebattery 11 via a conductor 64, and the relay coil 54 is connected withthe positive terminal of the battery 11 via conductors 64 and 66. Thenegative terminal of the battery 11 is connected to a ground G When therelay coil 54 is de-energized, the two movable contacts 51 and 52 arespring biased into engagement with the fixed contacts 49 and 50,respectively, and thereby define an electrical path in one direction tothe armature winding as will later be described. When the relay coil 54is energized, the two movable contacts 51 and 52 are caused to moveconcurrently into engagement with the fixed contacts 48 and 47,respectively, and thereby reverse-the direction of the electrical path20 to the armature winding to reverse the direction of rotation of thearmature 34, as will later be described.

The position switch means 28 comprises four switches 67a-67d which arepositioned adjacent and in a spaced circular relationship about theouter periphery of the drive shaft 22. With the drive shaft 22 in theposition shown in FIG. 2 wherein the windshield wiper arm and bladeassembly 14 is in its depressed park position P, as shown in FIG. 1, theclockwise sequence of the switches 67a-67d from the cam 22a is theswitch 670, the switch 67b, the switch 67c, and the switch 67d. Switch67a is approximately 15 clockwise from the position of the cam 22acorresponding to the depressed park position P of assembly 14, andswitch 67d is located a first predetermined angle in a clockwisedirection from switch 67a, which is approximately 330. Switch 670 isapproximately clockwise from the position of the cam 22a correspondingto the depressed park position P of assembly 14, and switch 67b islocated a second predetermined angle in a counterclockwise directionfrom switch 670, which is approximately 90. The switches 67d and 67 ccomprise a pair of movable contacts or leaf springs 68 and 69,respectively, which are normally self-biased out of engagement with apair of fixed contacts 70 and 71 to a normal open circuit position. Theswitches 67a and 67b comprise a pair of movable contacts or leaf springs72 and 73, respectively, which are normally self-biased into engagementwith a pair of fixed contacts 74 and 75 to a normal closed circuitposition. The movable contacts 68-72 of the switches 67a-67 arepositioned adjacent the outer periphery of the drive shaft 22 in amanner such that, upon rotation of the drive shaft 22, the cam 22a iscaused to engage and move each of the movable contacts in sequence fromits normal position to either an open or closed circuit position, aswill later be described in more detail.

The windshield wiper system is activated when the control bar 37 of themanual control switch means 24 is moved to its first on position inwhich it connects stationary contacts 42 and 43 with ground G,. In thismanner, the armature winding on the armature 34 is energized through acircuit traced from the positive terminal of the battery 1 l, conductor64, movable contact 51, fixed contact 49, conductor 60, fixed contact47, conductor 62, the armature winding, conductor 58, fixed contact 48,conductor 56, fixed contact 50, movable contact 52, a conductor 77,through fixed contacts 42, to the first contact portion 39 and to groundG and through ground to the negative terminal of the battery 11. Theenergization of the armature winding causes the armature 34 and thedrive shaft 22 attached thereto to rotate in a clockwise manner from theposition shown in FIG. 2. As the cam 22a is rotated with the drive shaft22 to a position immediately adjacent the movable contact 72, the driveshaft 22 pivots the windshield wiper arm and blade assembly 14 throughthe drive linkage 12 from its depressed park position P through angle Cto its inboard stroke end A,. As the drive shaft 22 and the cam 22a arerotated clockwise from immediately adjacent movable contact 72 to aposition 180 from the position shown in FIG. 2, the windshield wiper armand blade assembly 14 is pivoted by the linkage means 12 from theinboard stroke end A through the angular stroke A to the outboard strokeend A That position, which is approximately 180 from the position of thecam 22a shown in FIG. 2, is the throw-over or reversal point for thelinkage means 12. Further clockwise rotation of the drive shaft 22thereafter results in the linkage means 12 reversing the direction ofmovement of assembly 14. Therefore, the assembly 14 is driven from theoutboard stroke end A through the angular stroke A to the inboard strokeend A as the cam 22a completes the first predetermined angular movementbetween the switches 67a and 67d, whereupon the cam 22a engages andmoves the movable contact 68 to its closed circuit position. When thisoccurs, the relay coil 54 is energized through a circuit traced from thepositive terminal of the battery 11, the conductor 64, the conductor 66,the relay coil 54, a conductor 78, the movable contact 72, the fixedcontact 74, the conductors 79 and 80, the movable contact 73, the fixedcontact 75, the conductors 80a-82, the fixed contact 70, the movablecontact 68, the conductor 83, through the stationary contact 43, to thecontact portion 39 and to ground G and through ground to the negativeterminal of the battery 1 1. The energization of the relay coil 54causes the movable contacts 51 and 52 of the relay operated switch means26 to be moved concurrently into en gagement with the fixed contacts 48and 47, respectively. Accordingly, this results in the direction of theelectrical path through the DC motor 32 being reversed as will be seenby tracing the circuit from the positive terminal of the battery 11, theconductor 64, the movable contact 49, fixed contact 48, the conductor58, the armature winding of the armature 34, the conductor 62, the fixedcontact 47, the movable contact 52, the conductor 77, through thestationary contact 42, to the contact portion 39 and to ground G andfrom ground to the negative terminal of the battery 1 1.

It should be appreciated that the reversal of the electrical paththrough the armature 34 of the DC motor 20 causes the armature 34 andthe drive shaft 22 to reverse their direction of rotation from clockwiseto counterclockwise.

It should be noted that, as the drive shaft 22 rotates the cam 22athrough the first predetermined angle A, the cam closes the switch 67cand opens the switch 67b, as will later be described. This has, however,no effect upon the system 10 because the switch 67b is shorted through acircuit traced through conductors and 81, stationary contact 44, andconductors and 80 and the switch 67c is not grounded through fixedterminal 45.

With the reversal in the direction of rotation of the armature 34 andthe drive shaft 22 from clockwise to counterclockwise, the cam 22a iscaused to disengage the movable contact 68. The movable contact '68returns to its normal open circuit position as the cam 22a is disengagedtherewith. However, the relay coil 54 remains energized and thedirection of rotation of the armature 34 and the drive shaft 22continues in a counterclockwise direction. The relay coil 54 remainsenergized through a circuit traced from the positive terminal of thebattery 11, the conductors 64 and 66, the relay coil 54, the conductor78, the movable contact 72, the fixed contact 74, the conductor 79, theconductor 85, the fixed contact 44, the second contact portion 40, theconductors 81 and 82, a conductor 86, a diode 87, the conductor 86a, theconductor 62, the fixed contact 47, the movable contact 52, theconductor 77, through the stationary contacts 42, to the contact portion39 and to ground 6,, and through ground to the negative terminal of thebattery 11. As the drive shaft 22 rotates in a counterclockwisedirection through the first predetermined angle A, it should beappreciated that the windshield wiper arm and blade assembly 14 ispivoted by the linkage means 12 through a complete wipe cycle having anangular stroke similar to that previously described. The relay coil 54is maintained energized until the cam 22a completes a movement throughthe first predetermined angle in a counterclockwise direction from themovable contact 68 whereupon the cam 22a engages the movable contact 72and moves it to an open circuit position to de-energize the relay coil54. The de-energization of the relay coil causes the movable contacts 51and 52 of the relay operated switch means 26 to be moved concurrentlyinto engagement with the fixed contacts 49 and 50,

respectively. In a manner similar to that previously described, thedirection of rotation of the armature 34 and the drive shaft 22 isreversed again from counterclockwise to clockwise, and the windshieldwiper arm and blade assembly 14 is driven through yet another wipecycle.

From the foregoing, it should be understood that when the manual controlswitch 24 is in its first on position the direction of rotation of thearmature 34 and the drive shaft 22 is periodically reversed and thewindshield wiper arm and blade assembly 14 is oscillated by the linkagemeans 12 at a first wipe frequency and through a wipe cycle having afirst angular stroke A.

When the control bar 37 is moved to the second on position and uponrotation of the cam 22a through the second predetermined angle from theswitch 67b to the switch 670, the cam engages and moves the movablecontact 69 to its closed circuit position, and the relay coil 54 isenergized through a circuit traced from the positive terminal of thebattery 11, the conductors 64 and 66, the relay coil 54, the conductor78, the movable contact 72, the fixed contact 74, the conductors 79 and80, the movable contact 73, the fixed contact 75, the conductor 80a, aconductor 89, the movable contact 69, the fixed contact 71, a conductor90, through the fixed contact 45, to the contact portion 39 and toground 6,, and through ground to the negative terminal of the battery11. The direction of rotation of the armature 34 and the drive shaft 22is thereby reversed to counterclockwise. Further, when the cam 22a is ina position immediately adjacent the switch 670, the windshield wiper armand blade assembly 14 is at the outboard stroke end B of the angularstroke B. When the direction of rotation of the drive shaft 22 reversesto counterclockwise, the cam 30 is caused to disengage the movablecontact 69 which is then spring biased to its normal open circuitposition. The relay coil 54, however, remains energized through acircuit traced from the positive terminal of the battery 11, theconductors 64 and 66, the relay coil 54, the conductor 78, the movablecontact 79, the fixed contact 74, the conductors 79 and 80, the movablecontact 73, the fixed contact 75, the conductors 80a, 81, 82, 86, thediode 87, the conductor 860, the conductor 62, the fixed contact 47, themovable contact 52, the conductor 77, through the stationary contact 42,to the contact portion 39 and to ground G,, and through ground to thenegative terminal of the battery 11. During the counterclockwisemovement of the drive shaft 22 through the second predetermined anglebetween the switches 67bc, the drive linkage 12 drives the assembly 14from the outboard stroke end B through the angular stroke B to theinboard stroke end B After the second predetermined angular movement ofthe cam 22a in a counterclockwise direction from the movable contact 69to the movable contact 73, the cam 22a is caused to engage and move themovable contact 73 to its open circuit position and thereby de-energizethe relay coil 54. As previously described, the de-energization of therelay coil 54 results in reversal in the direction of rotation of thearmature 34 and the drive shaft 22 to clockwise. During the followingclockwise movement of the drive shaft 22 through the secondpredetermined angle between the switches 67b-c, the drive linkage l2drives the assembly 14 from the inboard stroke end B through the angularstroke B to the outboard stroke end B2.

Unlike the situation where the control bar 37 is in its first positionand movement of the drive shaft 22 through the first predetermined angleresults in the linkage means 12 driving the assembly 14 through a fullwipe cycle, movement of the drive shaft 22 through the secondpredetermined angle results in the linkage means 12 driving the assembly14 through only one angular stroke B. The assembly 14 is oscillatedthrough a -wipe cycle having an angular stroke B by reversal of themotor 20 not by the linkage means 12 because the posi tion of switches67b-c never allows the drive shaft 22 to pass the throw-over or reversalpoint for the linkage means. Further, because the second predeterminedangle is less than one-half the first predetermined angle, the angularstroke B is less than the angular stroke A and, because the assembly 14travels a shorter distance through a wipe cycle having an angular strokeB than one with an angular stroke A, the wipe frequency is greater whenthe contact bar 37 is in its second position than when it is in itsfirst position.

The windshield wiper system 10 also includes depressed park switch meanscomprising a fixed contact 93 and a movable contact 92 which isconnected to ground G In operation, the depressed park switch means 91serves as a holding circuit. The movable contact 92 is normally springbiased into engagement with the fixed contact 93 to a normal closedcircuit position. The movable contact 92 is responsive to a second cam95 fixed on the drive shaft 22 and is moved to an open circuit positionwhen the cam 95 reaches the position shown in Fig. 2.

When the contact bar 37 is moved from either its first on or second onpositions to its off position, the stationary contacts 42 and 43 or 45are no longer grounded to ground G and, ordinarily, the DC motor 20would be de-energized regardless of the position of the windshield wiperarm and blade assembly 14. The DC motor 20 is, however, maintained in anenergized state when the contact bar 37 is moved to its off positionthrough a circuit traced from the positive terminal of the battery 11,the conductor 64, the relay operated switch means 26, the conductor 77,a conductor 97, the fixed contact 93, the movable contact 92 to ground Gand through ground to the negative terminal battery 11. Further, whenthe contact bar 37 is moved to its off position, the relay coil, if notalready, is de-energized, thereby providing for the armature 34 and thedrive shaft 22 to be rotated in a clockwise direction. As the cam 22aengages and moves the movable contacts 68 and 69 to their closed circuitpositions, no effect is bad on the DC motor 20 because the stationarycontacts 43 and 44 are not grounded through the contact bar 37.Therefore, the drive shaft 22 continues to rotate in a clockwisedirection beyond the movable contact 68 to the position shown in FIG. 2.This additional clockwise movement of the drive shaft 22 moves thewindshield wiper arm and blade assembly 14, which has reached the innerend A, of the first angular stroke A when the cam 22a moves movablecontact 68 to its closed circuit position, through the angle C, as shownin FIG. 1, and to its depressed park position P immediately adjacent thebottom of the windshield 16. When the windshield wiper arm and bladeassembly 14 reaches its depressed park position, the cam 95 engages andmoves the movable contact 92 to its open circuit position which servesto de-energize the DC motor 20.

The foregoing disclosure relates only one embodiment of the inventionwhich may be modified withing the scope of the appended claims.

What is claimed is:

1. A windshield wiper system comprising: a reversible electric motormeans adapted to be connected with a power source and driving a driveshaft means for oscillating a windshield wiper; manual switch meansconnected with said motor means and having first and second on positionsfor controlling energization of said motor means; relay operated switchmeans operatively connected with said motor means and said manual switchmeans for reversing the direction of rotation of said motor means; cammeans rotatable with said drive shaft means; a plurality of positionswitches interconnected with said relay operated switch means and saidmanual switch means for controlling energization and de-energization ofsaid relay operated switch means to effect periodic reversal of saidmotor means, said position switches being actuated by said rotatable cammeans and effecting continuous oscillation of the wiper through a wipecycle having a first angular stroke when the manual switch is in itsfirst on position and effecting continuous oscillation of the wiperthrough a wipe cycle having a second angular stroke which is less thansaid first stroke when the manual switch is in its second on position.

2. A windshield wiper system comprising: a reversible, single speedelectric motor means operatively connected with a DC power source anddriving a drive shaft means for oscillating a windshield wiper means;manual switch means connected with said motor means and having first andsecond on positions for controlling energization of said motor means; arelay having a relay coil and associated switch means, said switch meansbeing connected with said motor means and said manual switch means forreversing the electrical path from the power source through said motormeans to reverse the direction of rotation of said motor means; cammeans rotatable with said drive shaft means; position switch meansconnected between said relay coil and said manual switch means foralternately energizing and de-energizing said relay in response to firstpredetermined angular movements of said cam means to periodicallyreverse the direction of rotation of said motor means to oscillate thewiper means at a first wipe frequency and through a wipe cycle having afirst angular stroke when said manual switch means is in its first onposition and for alternately energizing and de-energizing said relay inresponse to second predetermined angular movement of said cam means lessthan said first predetermined angular movements to reverse the directionof rotation of said motor means periodically faster when said manualswitch means is in the second on position whereby said motor meansoscillates the wiper means at a second wipe frequency greater than saidfirst wipe frequency and through a wipe cycle having a second angularstroke less than said first angular stroke when the manual switch meansis in its second on position.

3. A windshield wiper system comprising: a reversible, single speedelectric motor means driving a'drive shaft means for oscillatingwindshield wiper means and operatively connected with a DC power source;manual switch means connected with said motor means and having first andsecond on positions for controlling energization of said motor means bya power source; a relay having a relay coil and associated switch means,said associated switch means connected with said motor means and saidmanual switch means for reversing the electrical path from the powersource through said motor means to reverse the direction of rotation ofsaid motor means; cam means rotatable with said drive shaft; firstposition switch means interconnected between said relay coil and saidmanual switch means and responsive to first predetermined angularmovements less than one full rotation of said cam means for alternatelyenergizing and de-energizing said relay to periodically reverse thedirection of rotation of said motor means to oscillate the wiper meansat a first wipe frequency and through a wipe cycle having a firstangular stroke when said manual switch means is in its first onposition; and second position switch means connected between said relaycoil and said manual switch means and responsive to second predeterminedangular movements of said cam means less than said first angularmovements for alternately energizing and de-energizing said relay toreverse the direction of rotation of said motor means periodicallyfaster when said manual switch means is in its second on positionwhereby said motor means oscillates the wiper means at a second wipefrequency greater than said first wipe frequency and through a wipecycle having a second angular stroke less than said first angular strokewhen said manual switch means is in its second on position.

4. A windshield wiper system comprising: a reversible, single speedelectric motor means driving a drive shaft means for driving'windshieldwiper means and operatively connected with a DC power source; manualswitch means connected with said motor means and having first and secondon positions for controlling energization of said motor means by a powersource; a double pole, double throw relay connected with said motormeans and having a relay coil connected with said manual switch meansfor reversing the electrical path from the power source through saidmotor means when said relay coil is energized to reverse the directionof rotation of said motor means; cam means rotatable with said driveshaft; first position switch means connected between said relay coil andsaid manual switch means and comprising first and second switchesresponsive to first predetermined angular movements less than one fullrotation of said cam means for alternately energizing and de-energizingsaid relay coil to periodically reverse the direction of rotation ofsaid motor means to oscillate the wiper means at a first wipe frequencyand through a first wipe cycle having a first angular stroke when saidmanual switch means is in its first on position; and second positionswitch means also connected between said relay coil and said manualswitch means and comprising third and fourth switches responsive tosecond predetermined angular movements of said cam means less than onehalf said first predetermined angular movements for alternatelyenergizing and de-energizing said relay coil to reverse the direction ofrotation of said motor means periodically faster when said manual switchmeans is in its second on position whereby said motor means oscillatesthe wiper means at a second wiper frequency greater than said first wipefrequency and through a wipe cycle having a second angular stroke lessthan said first angular stroke when said manual switch means is in itssecond on position.

5. A windshield wiper system for an automotive vehicle comprising: adirect voltage source; windshield wiper means; a reversible single speedDC motor driving a drive shaft for driving linkage means; linkage meansfor normally oscillating said windshield wiper means through a fullwiper cycle for each full rotation of said drive shaft; a manual controlswitch having first and second on positions; means for connecting saiddirect voltage source, said motor, and said manual control switch toprovide for actuation of said windshield wiper means by said motor whensaid manual control switch is moved to said first and second onpositions; a double pole, double throw relay having its contactsconnected between said direct voltage source and said motor and having arelay coil for reversing the electrical path through said motor whenenergized and deenergized to reverse the direction of rotation of saiddrive shaft means of said motor to oscillate said windshield wipermeans; means for connecting said relay coil with said manual controlswitch; cam means rotatable with said drive shaft means; a first switchbiased to a normal open circuit position and a second switch biased to anormal closed circuit position and which are interconnected between saidrelay coil and said manual control switch, said first switch beingengaged and moved to a closed circuit position upon a relay coilenergized after said first switch moves to said open circuit positionand being engaged by said cam means upon another first predeterminedangular movement of the cam means in the opposite direction to be movedto an open circuit position to de-energize said relay coil and reversethe direction of rotation of said motor when said manual control switchis in its first on position whereby said motor drives said linkage meanswhich oscillates the wiper, means at a first wipe frequency and througha wipe cycle having a first angular stroke for each first predeterminedangular movement of said drive shaft; a third switch spring biased to anormal open circuit position and a fourth switch biased to a normalclosed position and which are interconnected between said relay coil andsaid manual control switch, said third switch being engaged and moved toa closed circuit position by said cam means upon a second predeterminedangular movement in one direction of said cam means less than one-halfsaid first angular movement to energize said relay coil to reverse thedirection of rotation of said motor when said manual switch means is insaid second on position and said third switch being operative to move tosaid normal 0 en circuit osition u n disen a ement b said cam nieans,said l ourth swl h serving t maintaih said relay coil energized aftersaid third switch moves to said normal open circuit position and beingengaged and moved to an open circuit position by said cam means uponanother second predetermined angular movement in the opposite directionto de-energize said relay coil to reverse the direction of rotation ofsaid motor when said manual control switch is in its second on positionwhereby said motor is reversed periodically faster and drives saidlinkage means which oscillates the wiper means at a second wipefrequency greater than said first wipe frequency and through a wipecycle having a second angular stroke less than said first an gularstroke for every two second predetermined angular movements of saiddrive shaft when said manual switch means is in its second on position.

1. A windshield wiper system comprising: a reversible electric motormeans adapted to be connected with a power source and driving a driveshaft means for oscillating a windshield wiper; manual switch meansconnected with said motor means and having first and second on positionsfor controlling energization of said motor means; relay operated switchmeans operatively connected with said motor means and said manual switchmeans for reversing the direction of rotation of said motor means; cammeans rotatable with said drive shaft means; a plurality of positionswitches interconnected with said relay operated switch means and saidmanual switch means for controlling energization and de-energization ofsaid relay operated switch means to effect periodic reversal of saidmotor means, said position switches being actuated by said rotatable cammeans and effecting continuous oscillation of the wiper through a wipecycle having a first angular stroke when the manual switch is in itsfirst on position and effecting continuous oscillation of the wiperthrough a wipe cycle having a second angular stroke which is less thansaid first stroke when the manual switch is in its second on position.2. A windshield wiper system comprising: a reversible, single speedelectric motor means operatively connected with a DC power source anddriving a drive shaft means for oscillating a windshield wiper means;manual switch means connected with said motor means and having first andsecond on positions for controlling energization of said motor means; arelay having a relay coil and associated switch means, said switch meansbeing connected with said motor means and said manual switch means forreversing the electrical path from the power source through said motormeans to reverse the direction of rotation of said motor means; cammeans rotatable with said drive shaft means; position switch meansconnected between said relay coil and said manual switch means foralternately energizing and de-energizing said relay in response to firstpredetermined angular movements of said cam means to periodicallyreverse the direction of rotation of said motor means to oscillate thewiper means at a first wipe frequency and through a wipe cycle havIng afirst angular stroke when said manual switch means is in its first onposition and for alternately energizing and de-energizing said relay inresponse to second predetermined angular movement of said cam means lessthan said first predetermined angular movements to reverse the directionof rotation of said motor means periodically faster when said manualswitch means is in the second on position whereby said motor meansoscillates the wiper means at a second wipe frequency greater than saidfirst wipe frequency and through a wipe cycle having a second angularstroke less than said first angular stroke when the manual switch meansis in its second on position.
 3. A windshield wiper system comprising: areversible, single speed electric motor means driving a drive shaftmeans for oscillating windshield wiper means and operatively connectedwith a DC power source; manual switch means connected with said motormeans and having first and second on positions for controllingenergization of said motor means by a power source; a relay having arelay coil and associated switch means, said associated switch meansconnected with said motor means and said manual switch means forreversing the electrical path from the power source through said motormeans to reverse the direction of rotation of said motor means; cammeans rotatable with said drive shaft; first position switch meansinterconnected between said relay coil and said manual switch means andresponsive to first predetermined angular movements less than one fullrotation of said cam means for alternately energizing and de-energizingsaid relay to periodically reverse the direction of rotation of saidmotor means to oscillate the wiper means at a first wipe frequency andthrough a wipe cycle having a first angular stroke when said manualswitch means is in its first on position; and second position switchmeans connected between said relay coil and said manual switch means andresponsive to second predetermined angular movements of said cam meansless than said first angular movements for alternately energizing andde-energizing said relay to reverse the direction of rotation of saidmotor means periodically faster when said manual switch means is in itssecond on position whereby said motor means oscillates the wiper meansat a second wipe frequency greater than said first wipe frequency andthrough a wipe cycle having a second angular stroke less than said firstangular stroke when said manual switch means is in its second onposition.
 4. A windshield wiper system comprising: a reversible, singlespeed electric motor means driving a drive shaft means for drivingwindshield wiper means and operatively connected with a DC power source;manual switch means connected with said motor means and having first andsecond on positions for controlling energization of said motor means bya power source; a double pole, double throw relay connected with saidmotor means and having a relay coil connected with said manual switchmeans for reversing the electrical path from the power source throughsaid motor means when said relay coil is energized to reverse thedirection of rotation of said motor means; cam means rotatable with saiddrive shaft; first position switch means connected between said relaycoil and said manual switch means and comprising first and secondswitches responsive to first predetermined angular movements less thanone full rotation of said cam means for alternately energizing andde-energizing said relay coil to periodically reverse the direction ofrotation of said motor means to oscillate the wiper means at a firstwipe frequency and through a first wipe cycle having a first angularstroke when said manual switch means is in its first on position; andsecond position switch means also connected between said relay coil andsaid manual switch means and comprising third and fourth switchesresponsive to second predetermined angular movements of said cam meansless than one half said first predetermined angular mOvements foralternately energizing and de-energizing said relay coil to reverse thedirection of rotation of said motor means periodically faster when saidmanual switch means is in its second on position whereby said motormeans oscillates the wiper means at a second wiper frequency greaterthan said first wipe frequency and through a wipe cycle having a secondangular stroke less than said first angular stroke when said manualswitch means is in its second on position.
 5. A windshield wiper systemfor an automotive vehicle comprising: a direct voltage source;windshield wiper means; a reversible single speed DC motor driving adrive shaft for driving linkage means; linkage means for normallyoscillating said windshield wiper means through a full wiper cycle foreach full rotation of said drive shaft; a manual control switch havingfirst and second on positions; means for connecting said direct voltagesource, said motor, and said manual control switch to provide foractuation of said windshield wiper means by said motor when said manualcontrol switch is moved to said first and second on positions; a doublepole, double throw relay having its contacts connected between saiddirect voltage source and said motor and having a relay coil forreversing the electrical path through said motor when energized andde-energized to reverse the direction of rotation of said drive shaftmeans of said motor to oscillate said windshield wiper means; means forconnecting said relay coil with said manual control switch; cam meansrotatable with said drive shaft means; a first switch biased to a normalopen circuit position and a second switch biased to a normal closedcircuit position and which are interconnected between said relay coiland said manual control switch, said first switch being engaged andmoved to a closed circuit position upon a first predetermined angularmovement less than one full rotation of said cam means in one directionto energize said relay coil to reverse the direction of rotation of saidmotor when said manual switch means is in said first on position andupon disengagement with said cam means being operative to move to saidopen circuit position, said second switch serving to maintain said relaycoil energized after said first switch moves to said open circuitposition and being engaged by said cam means upon another firstpredetermined angular movement of the cam means in the oppositedirection to be moved to an open circuit position to de-energize saidrelay coil and reverse the direction of rotation of said motor when saidmanual control switch is in its first on position whereby said motordrives said linkage means which oscillates the wiper means at a firstwipe frequency and through a wipe cycle having a first angular strokefor each first predetermined angular movement of said drive shaft; athird switch spring biased to a normal open circuit position and afourth switch biased to a normal closed position and which areinterconnected between said relay coil and said manual control switch,said third switch being engaged and moved to a closed circuit positionby said cam means upon a second predetermined angular movement in onedirection of said cam means less than one-half said first angularmovement to energize said relay coil to reverse the direction ofrotation of said motor when said manual switch means is in said secondon position and said third switch being operative to move to said normalopen circuit position upon disengagement by said cam means, said fourthswitch serving to maintain said relay coil energized after said thirdswitch moves to said normal open circuit position and being engaged andmoved to an open circuit position by said cam means upon another secondpredetermined angular movement in the opposite direction to de-energizesaid relay coil to reverse the direction of rotation of said motor whensaid manual control switch is in its second on position whereby saidmotor is reversed periodically faster and drives said linkage meanswhicH oscillates the wiper means at a second wipe frequency greater thansaid first wipe frequency and through a wipe cycle having a secondangular stroke less than said first angular stroke for every two secondpredetermined angular movements of said drive shaft when said manualswitch means is in its second on position.